Electric circuit breakers of the type which are temporarily pneumatically opened



4, 1954 H. A. HIDDE NIJLAND 3,143,612

ELECTRIC CIRCUIT BREAKERS OF THE TYPE WHICH ARE TEMPORARILYPNEUMATICALLY OPENED Filed Jan. 18, 1962 INVENTOR HENDR\K A. HIDDE.NHL-AND ATTORNEYS nied W3 P t? Hidde Nijland, executrix of said HendrikA. Hidde' Nijland,'deceased, assignor to N.V. CO2, Utrecht, Netherlands,a limited company of the Netherlands Filed Jan. 18, 1962, Ser. No.167,034 Claims priority, application Netherlands Jan. 24, 1961 p v .6Claims. (Cl. 200-82) c The invention relates to an electro-circuitbreaker of the type, which is temporarily pneumatically opened andcomprises a fixed contact and a movable contact forced against saidfirst contact by a spring, said movable contact being mounted to beseparated from said fixed contact by a piston which is mounted forreciprocation in a cylinder and is moved when one side of the piston isexposed to gas, of which the pressure has reached a predetermined value,said piston being adapted to move with respect to the movable contactfreely along a predetermined distance and being forced by a spring intoa position ofrest, in which position said piston is exposed to the gaspressure with a portion of its active area only, the arrangement beingsuch as to permit the entire active area of the piston of being exposedto the gas pressure after the piston has been moved by the gas out ofits position of rest againstsaid spring and before it is coupled withthe movable contact.

An electric circuit breaker of this type is described in the US. PatentNo. 2,500,429. Inthis known circuit breaker the cylinder and the pistonhave additional portions with a reduced diameter. A piston having such areduced portion requires an axial dimension which is twice the dimensionof a normal piston as to ensure areliable seal in the two parts ofdifferent diameters of the cylinder. In order to obtain an accurate fitof the piston in the two partsof the cylinder the piston body and thecylinder must be machined very accurately and in different areas thereofthe tolerances of the variations of the dimensions of said bodies mustbe keptvery small. I In this knowncircuit breaker the lost motion of thepiston, which depends on the axial dimension of the portion of thepiston having the reduced diameter, extends through a rather greatdistance.

The invention has for its object to provide an electric circuit breakerof the type referred to, in which both the cylinder and the pistonconsist of one active cylindric part only, so that the manufacture isconsiderably simplified and further advantages to be describedhereinafter are obtained. It consists in that the active area of thepiston or the cylinder end wall facing said piston area is provided withan annular rib having a diameter which is smaller than that of thepiston and a ring of elastic material is provided on said cylinder endwall or said piston area, respectively, said cylinder end wall and theelastic ring, if provided on said wall, having exclusively inside oroutside the annular rib one or more passages for the supply of gas underpressure, said rib and said elastic ring being pressed against oneanother in a gas tight manner by the spring loading the piston, when thelatter is in its position of rest. In this construction not only theaxial dimension but also the lost motion of the piston may be madesmaller than those of the piston having a reduced portion, so that thecylinder may have a smaller axial dimension and the time passed betweenthe point of time, at which the gas under pressure is supplied, andthat, at which the switching-otf operation takes place, will be shorter.

To obtain a reliable seal between the cylinder spaces separated by theannular rib and the elastic ring it is recommended to give the annularrib such a cross-sectional 3,143,612 Patented Aug. 4, 1964 'ice profileas to have said rib pressed into the elastic ring with a sharp edge.Said cross-sectional profile may have the shape of a triangle of whichthe base faces the piston.

In order to prevent that due to gas leaking through the seal formed bythe rib and the ring of elastic material the pressure under the entireactive area of the piston would rise, when the pressure under thesmaller piston area increases and thereby the piston would be set inmotion before the gas pressure would have reached the desired value, thecylinder space, in which the gas pressure becomes last active, may beconnected with the atmosphere by a vent, when the piston is in itsposition of rest, said' vent being closed, as soon as the piston isexposed with its entire active area to the gas pressure. This ventenables the pressure under the piston area to remain equal to that ofthe atmosphere as long as the two parts of the active cylinder chamberare separated from another by the annular rib. This vent may open intothe inactive cylinder chamber and 'may' be closed by the piston itself.In that case an additional valve for closing the vent is dispensed with.

The invention will be elucidated with the aid of the accompanyingdrawing, which diagrammatically illustrates by way of example an .axialsectional View of the essential part of an electric circuit breaker ofthe type, which is temporarily pneumatically opened.

In the drawing 1 is a fixed contact provided with a terminal strip 2 forthe connection to the outer circuit. Cooperating with said fixed contactis a movable contact 3 which in the present case closes an opening 4 forthe discharge of extinguishing gas. The movable contact 3 has astem 5,which is passed through the'bottom 6 of a cylinder 7 and through a fixedcontact ring 8 also provided with a terminal strip 9.

A piston 10 is loosely mounted on the stem 5 in the cylinder 7.. Saidpiston is provided with an annular rib 11 having a triangular crossprofile and in its position of rest said piston is pressed with its ribagainst a ring 13 of elastic material by a'spring 12. The elastic ring13 lies on the cylinder bottom 6. In said position of rest the activecylinder chamber under the piston 10 is divided into two separated parts14 and 15. The part 14 of said cylinder chamber communicates throughpassages 16 made in the cylinder bottom 6 with the switching chamber 17,to which gas under pressure can be supplied through an aperture 18 madein the wall of a tube 19 of insulating materi'al: 'This tube keeps thefixed contact 1 and the ring contact 8 spacedapart and surrounds theswitching chamber 17. The contact pressure between the contacts 1 and 3is furnished by the spring 20.

When gas under pressure is admitted to the switching chamber 17 throughthe aperture 18, the pressure in said chamber and also in the cylinderspace 14 will rise. If the force exerted on the relevant portion of thepiston by the gas in the cylinder chamber 14 overcomes the force of thespring 12, which will happen when the pressure of the gas exceeds apredetermined value, the piston 10 is moved upwards and the gas underpressure is also admitted to the cylinder space 15, since the piston islifted with its rib 11 from the elastic ring 13 and the cylinder spaces14, 15 are brought into communication with one another. Thereafter thepiston is exposed with its entire active area to the gas pressure andowing thereto the piston is driven upwards with great force against acollar 21 provided on the stem 5 of the movable contact 3. As aconsequence thereof said contact is taken along with the piston againstthe force of the springs 12 and 20 and separated from the fixed contact1, whereby the opening 4 is opened and the gas, which is in theswitching chamber 17 under high pressure, is able to escape through saidopening with great force, so that the are established between thecontacts 1 and 3 is extinguished.

In the position of rest of the piston the cylinder space is connected bya by-pass passage or vent 22 to the chamber 23 which communicates withthe atmosphere. Said. vent makes that the pressure in the cylinder space15 is not able to rise when gas is leaking from. the cylinder space 14into the space 15 through the seal formed by. the rib 11 of the piston10 and the elastic ring 13 in the position of rest of the piston.However, as soon as the piston is moved upwards and gas under pressureis admitted to the cylinder space 15, the connection between thecylinder space 15 and the chamber 23 is interrupted by the piston 10, sothat also in the cylinder space 15 the pressure of the gas is permittedto rise;

It is observed that it is not necessary that the piston is driven by theextinguishing gas. The pneumatic switching-off operation of the circuitbreaker and the extinguishing of. the established arc may be effectedindependently from one another and by different fluids. The rib 11 maybe provided on the cylinder bottom 6 and the ring 13 may be attached tothe piston 10.

What I claim is:

1. A pneumatically openable electric circuit breaker comprising a fixedcontact, a movable contact, a spring tending to force said movablecontact against said fixed contact, a cylinder, a piston mounted forreciprocation in said cylinder and dividing said cylinder into anactive" chamber and an inactive chamber, passages for leading and thearea of the active face of the piston includes an annular rib formed onthe active face of the piston and a seat of elastic material on thecylinder onto which the rib is pressed by said second spring in theposition of rest of said piston.

3. An electric circuit breaker as claimed in claim 2 in which saidannular rib has a cross sectional profile including a sharp edge whichis pressed into said elastic seat gas under pressure into said activechamber and against an active face of said piston, a second springtending to force said piston into a position of rest, means dividing theactive cylinder chamber and the area of the active face of the pistoneach into two parts when the piston is in its position of rest andinoperative to so divide the piston and active chamber upon movement ofthe piston from itsposition of rest, the passages for supplying gasunder pressure opening into one of said parts of the active cylinderchamber, and coupling means for connecting said piston with said movablecontact to move the latter contact away from the fixed contact uponexposure. of the active face of the piston to gas pressure exceeding apredetermined value, said piston having a lost motion betweenitsposition of' rest and a coupling position in which it is connected tosaid movable contact by said coupling means, whereby the application ofgas under pressure exceeding said predetermined value acts first on onlypart ofv the active face of the piston to slowly move the piston'fromwhen the piston is in its position of rest.

. 4. An electric circuit breaker as claimed in claim 1 furthercomprising a vent passage connecting to atmosphere that part of theactive cylinder chamber separated from the part into which the gassupply passages open,

' said vent passage being closed by the piston when the piston is movedfrom its rest position towards the position for coupling the piston withthe movable contact. I

5. An electric circuit breaker according to claim 4 wherein said ventpassage communicates with said active and inactive gas chambers, thelatter being open to atmosphere.

I 6. A pneumatically openable electric circuit breaker comprising afixed contact, a movable contact, a spring tending to force said movablecontact against said fixed contact, a cylinder, a piston mounted forreciprocation in said cylinder, passages for leading gas under pressureinto said chamber and against one face of said piston, a second springtending to force said piston into a position of rest, means dividingsaid cylinder and the area of said one face of the piston into twoactive gas chambers when the piston is in its position of restandinoperative to separate said active chamber upon movement of thepiston from its position of rest, the passages for supplying gas underpressure opening intoone of said active chambers, and

its position of rest whichmovement takes up said lost motion and opensboth said chamber and piston parts to coupling means for connecting saidpiston with said movable contact to move the latter contact away fromthe fixed contact upon exposure of the piston to gas pressure exceedinga predetermined value, said piston having a lost motion between itsposition of rest and a coupling position in which it is connected tosaid movable contact by said coupling means.

References Cited in the file of this patent UNITED" STATES PATENTS693,416 Messicket a1. Feb. 18, 1902 2,091,904 Baumann Aug. 31, 19372,420,370 Hamilton May 13, 1947 2,556,209 Negro June 12, 1951 p FOREIGNPATENTS 1 813,229 France Feb. 22, 1937 UNITED STATES PATENT-OFFICECERTIFICATE ()F' COR-REGTION Patent No. 3,143,612 August 4, 1964 HendrikA. Hidde Nijland, deceased Elizabeth Hidde Nijland, executrix Itishereby eertifiedthat error appears in the. above numberedpatent-'reqiiring"correction and that the said Letters Patentshould read ascorrected below."

In the grant, lines 3 and 13, and in the heading to the printedspecification, line 7, for "'C'O2, each occurrence,

read "COQ,"

Signed and sealed this 22nd day vof December 1964. L

1sEAL")- EDWARD J. BRENNER?" Commissioner of Patents n t'estifi OfficerUNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION? Patent No.3,143,612

Hendrik A. [-11 August 4, 1964 dde Nijland,

Elizabeth Hid It is hereby deceased, de Nijland, executrix certifiedthat error appears in the. above numberedtpat ent reqiiringcorreetiohand that the said LettersPatent should read as cor-rectedbelow.

In the grant lines 3 and 13, and in the heading to the printedspecification, line 7, for read "COQ, -o

"'C02, each occurrence,

Signed and sealed this 22nd day of December 1964,

aRNEsT w. 4 SWIDER' Itl'e sting Officer EDWARD J. BRENNER Commissionerof Patents

1. A PNEUMATICALLY OPENABLE ELECTRIC CIRCUIT BREAKER COMPRISING A FIXEDCONTACT, A MOVABLE CONTACT, A SPRING TENDING TO FORCE SAID MOVABLECONTACT AGAINST SAID FIXED CONTACT, A CYLINDER, A PISTON MOUNTED FORRECIPROCATION IN SAID CYLINDER AND DIVIDING SAID CYLINDER INTO AN ACTIVECHAMBER AND AN INACTIVE CHAMBER, PASSAGES FOR LEADING GAS UNDER PRESSUREINTO SAID ACTIVE CHAMBER AND AGAINST AN ACTIVE FACE OF SAID PISTON, ASECOND SPRING TENDING TO FORCE SAID PISTON INTO A POSITION OF REST,MEANS DIVIDING THE ACTIVE CYLINDER CHAMBER AND THE AREA OF THE ACTIVEFACE OF THE PISTON EACH INTO TWO PARTS WHEN THE PISTON IS IN ITSPOSITION OF REST AND INOPERATIVE TO SO DIVIDE THE PISTON AND ACTIVECHAMBER UPON MOVEMENT OF THE PISTON FROM ITS POSITION OF REST, THEPASSAGES FOR SUPPLYING GAS UNDER PRESSURE OPENING INTO ONE OF SAID PARTSOF THE ACTIVE CYLINDER CHAMBER, AND COUPLING MEANS FOR CONNECTING SAIDPISTON WITH SAID MOVABLE CONTACT TO MOVE THE LATTER CONTACT AWAY FROMTHE FIXED CONTACT UPON EXPOSURE OF THE ACTIVE FACE OF THE PISTON TO GASPRESSURE EXCEEDING A PREDETERMINED VALUE, SAID PISTON HAVING A LOSTMOTION BETWEEN ITS POSITION OF REST AND A COUPLING POSITION IN WHICH ITIS CONNECTED TO SAID MOVABLE CONTACT BY SAID COUPLING MEANS, WHEREBY THEAPPLICATION OF GAS UNDER PRESSURE EXCEEDING SAID PREDETERMINED VALUEACTS FIRST ON ONLY PART OF THE ACTIVE FACE OF THE PISTON TO SLOWLY MOVETHE PISTON FROM ITS POSITION OF REST WHICH MOVEMENT TAKES UP SAID LOSTMOTION AND OPENS BOTH SAID CHAMBER AND PISTON PARTS TO GAS PRESSURE.